Alkenyl bisimidazole optical bleaching agents



United St t fQ ALKENYL BISIMIDAZOLE OPTICAL BLEACHIN AGENTS Julian Jacob L'eavitt, Plainfield, N. 1., assignor to American Cya'namid Company, New York, N. Y., a corporation of 'Maine l loDrawing. Application June '21, 1954;

3 Claims. (Cl. 260-240) This invention relates to new optical bleaching agents of the structure in which B and B are six-membered aromatic carbocyclic rings, R is a lower alkenyl radical, R" is lower alkenyl or H and R is a divalent aliphatic hydrocarbon radical of less than 5 carbon atoms, the number of carbon atoms being even and containing at least one double bond. The invention also relates to detergent compositions containing the above compounds and to textiles dyed therewith.

In "recent years the use of optical bleaching agents, sometimes called brighteners, has grown enormously. These compositions are colorless dyestufls exhibiting substantivity for fabrics, which, when exposed to ultraviolet radiation such as is contained in daylight, fluoresce in the blue range of the spectrum, thereby compensating for the slightly yellowish cast of most white fabrics. The fluorescence of the bleaching agents, while in the blue, varies somewhat in dominant wave length. Where the dominant wave length is longer, the blue fluorescence is considered to have a slightly green tinge, whereas a shorter dominant wavelength nearer the violet end of the spectrum results in a blue fluorescence which is referred to as being slightly reddish. For practical purposes, particularly for use in detergent compositions intended for the laundering of white fabrics, a neutral blue fluorescence is generally pref-- erable since a reddish blue fluorescence will tend to build up pink on the fiber with repeated launderings.

Another problem with the optical bleaching agents i presented by theirfastness to certain treatments which they may encounter in laundering operations.' Among these fastness characteristics, a resistance to decomposition or quenching of fluorescence by reason of the presence of hydrochlorites is an important one because in many laundering operations hypochlorites are used for chemical bleaching purposes. so important is a good resistance the absence of said fabrics. This is true because under normal laundering conditions, the bleach and'thedetergent containing the brightener may be introduced before the goods to be washed. Many optical bleaches have adequatestability to bleach once on the fiber but are rapidly destroye d in solution. It is 'a'particulai' advantage 2,773,869 Pate te D s; 1. 1 .9?6.

of our newproducts that they are stable to bleach in tl e laundering medium evn'in the absence of fabric. I

The l\I- 'substituted diir'nidazoles of the present invention exhibit a-desi rable neutral or slightly greenish bluefluores; cence and surprisingly, they exhibit an extraordinary resistance to loss in fluorescence by reason of attack by hypochlorites. The presence of low concentrations of hypo chlorites which wouldbetypical of many launderingopera tions results in virtually no diminution of blue fluorescence. i

It isvnot known why the compounds of the present. invention exhibit the high degree of stability against hypochlorites. The chemical structure is such thata chemist wouldbe led to expect that they would be reactive with hypochloritesby reason of the double bond present in' the alkenyl group attached to nitrogen in one of the diimidazole rings. In spite of the known reactivity of such been determined why the compounds of the present invention exhibit this extraordinary anomaly in chemical behavior, and it is not intended to limit the invention to any theory of their action. 1

Not only do the compounds of the present invention exhibit desirable blue fluorescence and possess a high degree of hypochlorite stability, but the chroma of the blue fluorescence is markedly greater than other optical bleaches which have acceptable hypochlorite stability, especially those optical brighteners which have a neutralor greenish blue hue of fluorescence. The higher value of chroma, which may be thought of quantitatively as'a greater purity of the blue fluorescence, permits a more intense optical bleaching action and is a factor in which the compositions of the present invention are superior to other hypochlorite fast optical bleaches. It is a further advantage of the products of this invention that they have high fluorescent strength, appreciably higher than that of many other hypochlorite fast types.

Of particular importance is the outstanding behavior of these products on non-cellulosic fibers, for example, acetate, nylon (both the poly(hexamethylenediamineadipi-- mide) and poly-e-aminocaprolactam types), and acrylic fibers such as Orlon. Most cellulosic brighteners have little or no aflinity for non-cellulosics and therefore exhibit no appreciable whitening action. However, the new products of my invention have good afiinity for both types of fibers. For optimum results the products may be Se.- lected depending on the end use. Thus, if whitening of ,non-cellulosics is of prime importance, the compounds in which R and R7 are alkenyl are particularly useful and if whitening of cellulosic materials is more important, the compounds in which R" is hydrogen are preferred. However, it is a definite advantage that where whitening of both types of fibers is needed, either type brightener may be used.

The present invention is not intended to be restrictedto any particular process of preparing the compositions-It is, however, an advantage of the invention that the cornpounds can be very simply prepared by easily controlled reactions giving good yields. The basic skeleton of the molecule can be prepared by reacting a dibasic acid with, ortho-phenylenediamine or an N-alkenyl derivative. The dibasic acid may be either saturated or unsaturated 21nd,. of course, should have a hydrocarbon chain connecting the two carboxyl groups which contains an even number of carbon atoms less than 5.. If an unsaturated dibasic acid is used, the group R will contain'at least one double bond. An example .of such a process is the reaction of ortho-phenylenediamine ora mono N-alkenyl g derivative with fumaric acid. It is'also possible to use" a saturated dibasic acid, suchias for example suceinic acid, which willinot produce the immediate precursor ofthe compounds of the present invention, but will produce compounds in which R' is a saturated hydrocarbon chain.

These can eas'ily be dehydrogenated withfsuchpornpou'ndsg as mercuricac'eta'te, ferric chloride and "the like. 1 After the unsaturated or saturated compound is, prepared, the alken'ylg'roup 'is introduced by reaction with 'an alkeriylating agent suchas an alkenyl halide. If initially a satu:

same situation existswith the methallyl radical. Among. the typioalagents usable for introducingfthe alkenyl group are allyl bromide, methallyl iodide and crotylchlor'ide."

The quantity of the alkenyl halide rnus't'be restrictedto approximately mole per mole' based on the diimidazole" if the mono-alkenyl derivative is desired. Y

It is an advantage of the presentinvention that the compounds may be used with the typical detergents, ex= amples of which are soaps, emulsifying agentssuch as sulfite cellulose waste liquor, alkyl naphthalene sulfonic acids, condensation products of naphthalene sulfonic acids with formaldehyde, sulfonated or sulfated oil's, sulfuric half esters of higher alcohols and the like.

As indicated above, the textiles which are treated with compositions containing the compounds of the present invention readily take up the optical bleaching agent, and it is an advantage that there is adequate substantivity for cellulosic fibers, cellulose esters,,basic nitrogen fibers such as'polyamides, polyesters, polyacrylonitriles and the like. Moreover, it is a particular advantage that these products have an excellent aifinity for fibers such as polyamides, e. g. nylon, even in the presence of cellulosic materials.

Most optical bleaches for cellulosic materials, especiallyv the hypochlorite fast products such as the benzidine sulfone derivatives, have little affinity for nylon and other non-cellulosic fibers, evenin the absence of cellulosic fibers. The dyed textiles show a remarkable whiteness which resists strongly the attack of hypochl-orites. The natural yellowish tinge of the fabric is completely masked by the high chroma and strong fluorescence of the compounds of the present invention.

The invention will be illustrated by the following specifi'c examples in which the parts are by weight unless otherwise indicated.

Example 1 i N N \CCH=CHC/ N1 N1 CaH's H A solution of 52 parts. of 1, 2-bis (Z-benzimidazolyl) ethylene in 400 parts of alcohol and 22.4 parts of potassium hydroxide is stirred under reflux. To this is added gradually an alcoholic solution of 26.6 parts of B-bromopropane-l." The mixture is stirred and boiled until the It is cooled to room temperature b iLI'filtered, washed and dried, giving a good yield of. It be precipitated again from alco.-.

a yellow solid which does not'melt below 320 C. desired, the material can h'olic alkaline solution.

There is some evidence that Example 2 N N a \N \N/ Theprocedure of. Example. 1 is. followed, using. an equivalent quantity of l, Z-bis (.Z-benzimidazolyl) ethane in place of the 1, 2-bis (Z-benzimidazolyl) ethylene. The-v productshows a weaker fiuoresjce'nce'than the' rpdnct. of Example I. on treatment with mercuric acetateinacetic acid solution, it is converted to a product identical to that of Examplel.

Example 3 o-orhon-o Example 4 ,e cn,=on-on=en-e The procedure of Example 1 is followed using an equivalent amount of 1, 4-bis (Z-behzir'nidaz'olyl) butad-iene in place of 1, 2-bis (Z-benZimidazolyl) ethylene}. A product of intense blue fluorescencein alcoholic solu tion is obtained.

Example 5 Usingthe procedure of Example l' but substituting 1,2-bis t5 6)-methyl 2-benzimidazolyl] ethylene, there 7 is obtainedthe expected allyl derivative. It isa yellow powder having an: intense blue fluorescence in alcohol solwtion. p v

Similarly the product containing chlorine in the 5 (6) position can be prepared.

Exam le 6 N CsHg. oaH' l A slurry of 26 parts of 1,2-bis(2-benzimidazolyl)ctliyl enein 4Q0 parts of ethanol and parts by volume-of 2 molar 'ethanolic potassium hydroxide is treated atthe boiling point With a solution of 24.2 parts 3-1bromo-- propene-1 in'80 parts of'ethanol'. The mixture is stirred at the 'boiling point under refi ux until the reaction is complete, cooled, filtered, and washed with ethanol. The, filtrate and washings are drowned into a large volume of water and the precipitate is isolated by filtration 'lt, can be purified by dissolving in hot aqueousalcoholic, hydrochloric acid, treating with activated charcoal and reprecipitating by the addition of ammonia. A good yield is obtained 'of'a yellow solid which -fluoresces 'strongly in alcoholic solution.

t mb 7 A 0.05%solution of .the. product of-Exa'mple- 1. ispreapared; in 5 0% aqueous dimethyltormamide; containinga small amount of sodium hydroxide and a trace of a nonionic dispersing agent. Fifty volumes of the solution is diluted to 500 volumes with water to give a 0.005% mixture (A). A 0.500% aqueous solution of detergent (B) is prepared by dissolving 5.0 parts of a commercial detergent in 500 parts of hot water and diluting to 1000 volumes with cold water. A 5-g. piece of cotton muslin is added to a mixture of parts of solution A, 100 parts of solution B and parts of water. After agitating twenty-five minutes at 130 F., the cloth is removed, rinsed in cold tap water, and air dried. The resultant product is much whiter in appearance than an undyed piece.

Nylon treated in the same manner is also much improved in whiteness.

The products of Examples 2, 3, 4, 5 and 6 give similar results when similarly used.

Example 8 I \O-OH2CH3O/ N t A slurry of 52.4 parts of 1,2-bis(2-henzimidazolyl)ethane in 240 parts of ethanol and 160 parts of 2 molar ethanolic potassium hydroxide is treated at the boiling point with a solution of 53.2 parts 3-bromopropene1 in 160 parts of ethanol. The mixture is heated under reflux until the reaction is substantially complete, cooled, filtered and washed with alcohol. The alcohol-soluble product is isolated from the filtrate and washings by in which R1 is allyl and R2 is chosen from the group consisting of hydrogen and allyl.

2. The compound of claim 1 in which R2 is hydrogen. 3. The compound of claim 1 in which R2 is allyl.

References Cited in the file of this patent UNITED STATES PATENTS 2,338,782 Reister Jan. 11, 1944 2,463,764 Graenacher May 1, 1949 2,488,094 Graenacher Nov. 15, 1949 2,488,289 Meyer Nov. 15, 1949 2,515,173 Ackerman July 18, 1950 2,548,571 Lare Apr. 10, 1951 2,623,879 Ringwald Dec. 30, 1952 

1. COMPOUNDS OF THE STRUCTURE: 